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Input requested - damping theory question

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Old   June 29, 2016, 16:14
Default Input requested - damping theory question
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Kegan Leckness
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Hi, all.

I'm modeling a foam earplug under blast conditions. Literature gives the loss factor as 0.5, which is modeled in ANSYS via beta-damping where

Beta = (loss factor)/(pi * frequency)
[which results in an exponential decay as frequency increases.]

As my blast analyses are in the time domain, I need to choose a single beta-damping factor to represent the loss factor.

How do I decide on the damping value?

Small damping values (i.e. damping at higher frequencies) give me better results, so I'd like to average Beta over the range of 20 - 20K Hz. However, energy spectral analysis (via FFT) shows the majority of the energy is concentrated in the lower frequencies.

Is it justifiable to use the average Beta across the human hearing frequency range?

Any input appreciated.
Thanks,
Kegan
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